In an oil or gas well, a stinger assembly may be attached to the lower end of an upper section of tubing to provide a releasable sealed connection with a well tool such as a tubing hanger or packer or the like which supports a lower section of tubing in the well. When installing the well tool in the well, it is desirable that the stinger be locked against separation from the well tool but, once the well tool is anchored in its desired position in the well, it may become necessary to disconnect the stinger from the well tool to allow the upper section of tubing to be pulled from the well for servicing. Apparatus connected to the tubing at the wellhead may make it desirable to be able to disconnect the stinger from the well tool without having to rotate the tubing or slide the upper section of tubing downwardly within the well.